Desirability of a watertight seal on a mask used for underwater diving is evident. Masks are designed to seal off the face from above the lip to above the eyes. The mask should also provide maximum visibility and comfort.
To test for proper fit, a diver places the mask against their face without a strap and breathes in. If the mask fits properly, it will remain on the face with no other support than the suction of breathing in. Typically, a supplier of masks must carry several sizes and styles to fit the many varied sizes and shapes of the human face.
U.S. Pat. No. 3,143,739, incorporated herein by reference, shows a face mask, which addresses the difficulty of obtaining a watertight seal by providing a specialized exhaust opening for removing water which seeps in.
U.S. Pat. No. 3,186,005, incorporated herein by reference, discloses a face mask which is designed to provide substantially unrestricted, distortion free visibility.
U.S. Pat. No. 4,112,521, discloses a quick adjust strap for a face mask. The strap attaches through a typical ring pivotally mounted within a hinge.
Presently, the problem of obtaining a good seal is addressed by use of an inner flap which extend around the perimeter of the soft part of the mask to form a second seal. This makes manufacture of the mask difficult and fails to address the difficulty of sizing.
The need exists for a mask which maximizes visibility, has a universal fit, and provides a good watertight seal.